Electric motor having rotor structure for avoiding defect due to strain generated by temperature change, and production method thereof

Abstract

An electric motor having a rotor structure and a production method thereof, wherein a strain due to temperature change does not occur and a manufacturing problem does not occur. Each permanent magnet does not contact each other, and a deformable intervening member is positioned between the end surfaces of the magnets. Intervening member is an elastically or plastically deformable member, and the thickness of the intervening member in the direction of the rotation axis of the rotor is determined so that the neighboring permanent magnets, which are bonded to a rotor core within a manufacturing temperature range of the rotor, do not contact each other at a lower limit of an operating temperature of the electric motor.

The invention claimed is: 
     
       1. A production method of an electric motor comprising a stator and a rotor configured to be rotated relative to the stator,
 wherein the method comprises the steps of:
 constituting a rotor core by stacking magnetic steel plates; 
 aligning a plurality of permanent magnets in a direction of a rotation axis of the rotor and fixing the permanent magnets to the magnetic steel plate by means of adhesives; 
 positioning an intervening member, which melts at a temperature higher than a curing temperature of the adhesives, between the permanent magnets which are adjacent to each other in the direction of the rotation axis; and 
 heating the rotor after the adhesives are cured so that the intervening member melts and flows from between neighboring permanent magnets, 
 wherein a thickness of the intervening member in the direction of the rotation axis is determined so that neighboring permanent magnets, which are bonded to the rotor core within a manufacturing temperature range of the rotor, do not contact each other at a lower limit of an operating temperature of the electric motor. 
 
 
     
     
       2. The production method as set forth in  claim 1 , comprising the step of alternately inserting the permanent magnet and the intervening member into a magnet insert hole which is formed in the rotor core. 
     
     
       3. The production method as set forth in  claim 1 , comprising the step of previously adhering the intervening member to an end surface of the permanent magnet which faces in the direction of the rotation axis.